We will purify leukocytes (neurophils, monocytes and eosinophils) from the blood of normal subjects and patients with selected disorders known to predispose to the development of mycotic infections. The leukocytes will be tested for their ability to kill Candida parapsilosis, Candida albicans, and certain other marker organisms. Leukocytes will be fractionated and components purified by electrophoretic and chromatographic techniques, and components with fungicidal activity will be identified and characterized. The mechanism of killing of fungi will be investigated by radioisotopic methods including release from pre-labelled yeast of radio-chromium, rubidium and 2-deoxyglucose, and effects on incorporation of amino acids and nucleotides, the kinetics and mechanism(s) of adsorption of leukocyte proteins to fungi will be investigated. BIBLIOGRAPHIC REFERENCES: Lehrer, Robert I. 1975. The Fungicidal Mechanisms of Human Monocytes. I. Evidence for myeloperoxidase-linked and myeloperoxidase-independent candidacidal mechanisms. J. Clin. Invest. 55: 338-346; Hohn, D.C. and Lehrer, R.I. 1975. Oxidase deficiency in x-linked chronic granulomatous disease. J. Clin. Invest. 55: 707-713.